DRUG INFO
Baclofen
Drug Name:
Baclofen
Indication: For the alleviation of signs and symptoms of spasticity resulting from multiple sclerosis, particularly for the relief of flexor spasms and concomitant pain, clonus, and muscular rigidity
Pharmacology: Baclofen is a muscle relaxant and antispastic. Baclofen is useful for the alleviation of signs and symptoms of spasticity resulting from multiple sclerosis, particularly for the relief of flexor spasms and concomitant pain, clonus, and muscular rigidity. Although Baclofen is an analog of the putative inhibitory neurotransmitter gamma-aminobutyric acid (GABA), there is no conclusive evidence that actions on GABA systems are involved in the production of its clinical effects. In studies with animals, Baclofen has been shown to have general CNS depressant properties as indicated by the production of sedation with tolerance, somnolence, ataxia, and respiratory and cardiovascular depression. Baclofen is rapidly and extensively absorbed and eliminated. Absorption may be dose-dependent, being reduced with increasing doses. Baclofen is excreted primarily by the kidney in unchanged form and there is relatively large intersubject variation in absorption and/or elimination.
Mechanism Of Action: Baclofen is a direct agonist at GABAB receptors. The precise mechanism of action of Baclofen is not fully known. It is capable of inhibiting both monosynaptic and polysynaptic reflexes at the spinal level, possibly by hyperpolarization of afferent terminals, although actions at supraspinal sites may also occur and contribute to its clinical effect.
Drug Category: Muscle Relaxants; Skeletal Muscle Relaxants; GABA Agonists; ATC:M03BX01
Brand Names/Synonyms: Apo-Baclofen; Ba 34647; Baclofen; Baclon; C 34647ba; Kemstro; Lioresal; Lioresal Intrathecal; Novo-Baclofen; Nu-Baclofen; Pms-Baclofen
Dosage Forms: TABLET; INTRATHECAL INJECTION;
Absorption: Rapidly and extensively absorbed
Interactions:
DrugBank: Interactions for Baclofen
Interactions for Baclofen:
Injection
There is inadequate systematic experience with the use of baclofen injection in combination with other medications
to predict specific drug-drug interactions. Interactions attributed to the combined use of baclofen injection and
epidural morphine include hypotension and dyspnea.
SIDE EFFECTS (KEMSTRO)
The most common adverse reaction during treatment with baclofen is transient drowsiness (10-63%).
In one controlled study of 175 patients, transient drowsiness was observed in 63% of those receiving baclofen
tablets compared to 36% of those in the placebo group. Other common adverse reactions are dizziness (5-15%), weakness
(5-15%) and fatigue (2-4%). Others reported:
Neuropsychiatric: Confusion (1-11%), headache (4-8%), insomnia (2-7%); and, rarely, euphoria, excitement,
depression, hallucinations, paresthesia, muscle pain, tinnitus, slurred speech, coordination disorder, tremor,
rigidity, dystonia, ataxia, blurred vision, nystagmus, strabismus, miosis, mydriasis, diplopia, dysarthria, epileptic
seizure.
Cardiovascular: Hypotension (0-9%). Rare instances of dyspnea, palpitation, chest pain, syncope.
Gastrointestinal: Nausea (4-12%), constipation (2-6%); and, rarely, dry mouth, anorexia, taste disorder,
abdominal pain, vomiting, diarrhea, and positive test for occult blood in stool.
Genitourinary: Urinary frequency (2-6%); and, rarely, enuresis, urinary retention, dysuria, impotence,
inability to ejaculate, nocturia, hematuria.
Other: Instances of rash, pruritus, ankle edema, excessive perspiration, weight gain, nasal
congestion.
Some of the CNS and genitourinary symptoms may be related to the underlying disease rather than to drug therapy.
The following laboratory tests have been found to be abnormal in a few patients receiving baclofen: increased SGOT,
elevated alkaline phosphatase, and elevation of blood sugar.
The adverse experience profile seen with KEMSTROTM was similar to that seen with baclofen tablets.
Chemical IUPAC Name: 4-amino-3-(4-chlorophenyl)-butanoic acid
Chemical Formula: C10H12ClNO2
Half Life: 1.51 hours
Drug Type: Approved Drug
# Accession No: APRD00551
CAS Registry Number: 1134-47-0
